At least 175 IndiGo flights were cancelled early on Thursday in India as chaos at key airports worsened, after stringent government regulations on crew safety norms threw roster planning at the country’s largest airline into disarray.

The disruptions have left thousands of travellers stranded for three days now.

IndiGo, which has a domestic market share of more than 60%, on Wednesday cancelled at least 150 flights across major cities.

On Thursday, 73 flights were cancelled at Bengaluru airport, its spokesperson said.

Around 30 were cancelled in Delhi, and 68 in Hyderabad, according to airport sources.

The airline did not respond to a request for comment on Thursday, but has said this week the cancellations were due to various factors, including stricter flight duty time limits introduced by India’s aviation regulator to tackle pilot fatigue.

The Federation of Indian Pilots said IndiGo was not able to make timely roster adjustments and plan its schedule properly ahead of a November 1 implementation date that increased rest periods and introduced some restrictions on night flying.

The crisis is a major setback for the two-decade-old airline that built its reputation on being punctual, coining the tagline “IndiGo Standard Time” when it shut plane gates well before departure time.

The airline’s statement on Wednesday said it was making “calibrated adjustments” to its schedules for the next two days.